CN116073771A - Solid state power source linearization system and method for particle accelerator - Google Patents
Solid state power source linearization system and method for particle accelerator Download PDFInfo
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Abstract
The invention relates to a solid state power source linearization system and method for a particle accelerator, wherein the system comprises a low level system, a solid state power source, a directional coupler and an input coupler; the output end of the low-level system is connected with the input end of the solid-state power source, the output end of the solid-state power source is connected with the input end of the directional coupler, the output end of the directional coupler is fed into the radio-frequency superconducting cavity through the input coupler, and the output end of the solid-state power source is also connected with the low-level system through the coupling end of the directional coupler. The invention realizes linearization of the solid-state power source by constructing the predistortion function, and the compensated power source can reach the loop gain similar to the linear region even if working in the near saturation region, thereby realizing the purpose of improving the operation efficiency of the accelerator.
Description
Technical Field
The invention relates to a solid-state power source linearization system and method for a particle accelerator, and relates to the field of particle accelerators.
Background
In recent years, solid state radio frequency power amplifiers have gained widespread use in the field of particle accelerators (especially continuous wave radio frequency superconducting accelerators) due to the rapid development of semiconductor technology. Compared with the traditional vacuum power device, the solid-state radio frequency power amplifier has the advantages of high reliability, high stability, high maintainability and the like. Therefore, the continuous wave radio frequency superconducting accelerator currently under construction, planning and planning at home and abroad mostly adopts a solid radio frequency power amplifier as a preferred solid power source.
However, solid state power sources present a serious problem in practical applications of particle accelerators. In order to improve the operation efficiency of the accelerator, the operating point of the solid-state power source needs to be close to the saturation region, which introduces nonlinear factors into the radio frequency system, and reduces the effective control gain of the radio frequency low-level control system (short for low level, which is a digital control unit for driving the solid-state power source and is used for ensuring the stability of the acceleration field of the superconducting cavity). In addition, solid state power sources also present non-linearity issues at small signal inputs compared to vacuum power devices, which can present other engineering challenges.
In summary, the non-linearity problem of solid state power sources not only limits the operating efficiency of current and future high power, high current high intensity rf superconducting accelerators, but also increases the complexity of machine operation.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. In view of the above, it is an object of the present invention to provide a solid state power source linearization system and method for a particle accelerator, which can solve the problem that the nonlinear characteristics of the solid state power source cannot meet the high efficiency operation of the accelerator.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
in a first aspect, the present invention provides a method for linearizing a solid state power source for a particle accelerator, comprising:
acquiring an input signal of a fixed power source;
and carrying out nonlinear compensation on the input signal of the solid-state power source according to the predistortion function.
Further, the superconducting cavity is detuned in advance, specifically: and adjusting the resonance frequency of the superconducting cavity by using the tuner, so that the resonance frequency of the superconducting cavity is smaller than the frequency of the radio frequency signal, and the detuning frequency is larger than 10 times of the bandwidth of the superconducting cavity.
Further, the obtaining of the predistortion function includes:
measuring an input-output nonlinear characteristic curve of the solid-state power source;
and calculating a predistortion function based on the input-output nonlinear characteristic curve, wherein the predistortion function comprises an amplitude predistortion function and a phase predistortion function.
Further, the input-output nonlinear characteristic curve of the solid-state power source comprises an AM-AM nonlinear characteristic curve and an AM-PM nonlinear characteristic curve, wherein AM-AM is an input amplitude to an output amplitude, and AM-PM is an input amplitude to an output phase.
Further, the magnitude predistortion function and the phase predistortion function are obtained by solving the measured solid-state power source response signal magnitude f (x) and phase θ (x), and include:
the solid-state power source has an input pulse amplitude of X sat Saturated output corresponding to Y sat ＝f(X sat )；
Function h (X) = (X) defining normalized AM-AM characteristic curve sat /Y sat )f(x)；
The magnitude predistortion function g (x) is the inverse of h (x) above, i.e., g (x) =h -1 (x)；
The phase predistortion function is a complex function phi (x) = -theta [ g (x) ].
Further, the amplitude predistortion function and the phase predistortion function are lookup tables, the lookup tables comprise addresses and data, the addresses of the lookup tables are the amplitude of the input pulse signals, and the data in the lookup tables are discrete values of the amplitude predistortion function or the phase predistortion function.
Further, the process of making the amplitude and phase lookup table includes:
discretizing g (x) and phi (x) into g (n) and phi (n) according to an amplitude predistortion function and a phase predistortion function, wherein the unsigned number n is the amplitude of the intercepted high 15-bit input pulse signal, and the value range is 0 to 32767;
when n is less than or equal to saturation point X sat When the predistortion functions g (X) and phi (X) are directly calculated, the values of x=0, 1,2 and … X sat The values at are g (n) and phi (n), when n is greater than saturation point X sat When g (n) and phi (n) are respectively constant equal to the constant g (X) sat ) Phi (X) sat )；
And writing g (n) and phi (n) into data in the amplitude or phase lookup table to obtain data corresponding to each address, and completing the manufacture of the amplitude or phase lookup table.
In a second aspect, the present invention provides a solid state power source linearization system for a particle accelerator, the system comprising a low level system, a solid state power source, a directional coupler, and an input coupler;
the output end of the low-level system is connected with the input end of the solid-state power source, the output end of the solid-state power source is connected with the input end of the directional coupler, the output end of the directional coupler is fed into the superconducting cavity through the input coupler, and the output end of the solid-state power source is also connected with the low-level system through the coupling end of the directional coupler.
Further, the low-level system is realized through an FPGA chip, and the FPGA chip comprises a sawtooth wave pulse signal generator and a predistortion module;
the sawtooth wave pulse signal generator is used for outputting sawtooth wave pulse to drive the solid-state power source;
the predistortion module is used for carrying out nonlinear compensation on an input signal of the solid-state power source according to the set predistortion function.
Further, the obtaining process of the predistortion function includes:
measuring an AM-AM nonlinear characteristic curve and an AM-PM nonlinear characteristic curve of a solid-state power source, wherein AM-AM is input amplitude to output amplitude, and AM-PM is input amplitude to output phase;
and calculating a predistortion function based on the AM-AM nonlinear characteristic curve and the AM-PM nonlinear characteristic curve, wherein the predistortion function comprises an amplitude predistortion function and a phase predistortion function.
The invention adopts the technical proposal and has the following characteristics:
1. the solid-state power source is a main source of nonlinearity of the radio frequency system, and the linearization of the solid-state power source is helpful for improving the operability of the accelerator radio frequency system.
2. Because the new generation particle accelerator system generally adopts a digital low-level technical scheme based on the FPGA, the predistortion module of the invention can be completely deployed inside the low-level system without adding additional hardware equipment.
3. According to the invention, the superconducting cavity is detuned in advance, so that the superconducting cavity fault caused by the measurement process is effectively avoided, the hardware equipment connection of the existing radio frequency system is not required to be changed during measurement, and all the measurement and verification can be performed on line.
4. According to the invention, the nonlinear characteristic curve of the solid-state power source is calculated according to the response function of the solid-state power source to the sawtooth wave pulse, the measurement process can realize full automation, a plurality of superconducting cavities can be measured simultaneously, and the measurement process can be completed rapidly during the aging of the superconducting cavities without occupying machine time.
In summary, the invention provides a fast and flexible on-line solid state power source linearization scheme, which can be widely applied to solid state power sources of particle accelerators.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Like parts are designated with like reference numerals throughout the drawings. In the drawings:
FIG. 1 is a flow chart of a method for linearizing a solid state power source in accordance with an embodiment of the invention;
FIG. 2 is a schematic diagram of a solid state power source linearization system in accordance with an embodiment of the invention;
FIG. 3 is a graph of the nonlinear characteristics of the solid state power sources AM-AM and AM-PM according to an embodiment of the invention;
FIG. 4 shows nonlinear characteristic functions f (x) and θ (x) and corresponding predistortion functions g (x) and φ (x) according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a predistortion module within a low level system FPGA chip according to an embodiment of the present invention;
fig. 6 (a) is an amplitude predistortion function g (x) according to an embodiment of the present invention, fig. 6 (b) is an amplitude predistortion function g (n) after discretization according to an embodiment of the present invention, and fig. 6 (c) is an address and data of an amplitude lookup table according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of an embodiment of the present invention for implementing nonlinear compensation of a solid state power source;
FIG. 8 is a diagram of an experimental scheme for measuring the overall nonlinear characteristic curves of a predistortion module and a solid state power source in accordance with an embodiment of the present invention;
FIG. 9 is a graph showing the comparison of AM-AM curves (left) and AM-PM curves (right) before and after linearization according to an embodiment of the invention; wherein:
the reference numerals in the drawings are: 1-low level system; 2-a solid state power source; a 3-directional coupler; a 4-input coupler; 5-radio frequency superconducting cavity.
Detailed Description
It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "includes," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless an order of performance is explicitly stated. It should also be appreciated that additional or alternative steps may be used.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
For ease of description, spatially relative terms, such as "inner," "outer," "lower," "upper," and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.
The non-linearity problem due to the solid state power source not only limits the operational efficiency of current and future high power, high current high intensity rf superconducting accelerators, but also increases the complexity of machine operation. The invention provides a solid-state power source linearization system and a method for a particle accelerator, comprising the following steps: according to the input and output signals of the solid-state power source, an input and output nonlinear characteristic curve of the solid-state power source is obtained; calculating a predistortion function according to an input-output nonlinear characteristic curve of the solid-state power source; and carrying out nonlinear compensation on the input signal of the solid-state power source according to the predistortion function obtained by calculation, so that the compensated power source can reach a loop gain similar to a linear region even if working in a near saturation region. Therefore, the invention can ensure that the solid-state power source of the particle accelerator can reach the loop gain close to the linear region when working near the saturation region, thereby taking the running efficiency of the particle accelerator and the control capability of the radio frequency system into account.
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Embodiment one: as shown in fig. 1, the solid-state power source linearization method for a particle accelerator provided in this embodiment includes:
s1, measuring an input-output nonlinear characteristic curve of a solid-state power source on line.
Specifically, as shown in fig. 2, the output of the low-level system 1 of the present embodiment is connected to the input of the solid-state power source 2, the output of the solid-state power source 2 is connected to the input of the directional coupler 3, and the output of the directional coupler 3 is fed into the radio-frequency superconducting cavity (referred to as superconducting cavity for short) through the input coupler 4. Wherein the output of the solid state power source 2 is connected to the low level system 1 via the coupling end of the directional coupler 3.
In order to measure the nonlinear characteristic curve of the solid-state power source online, the embodiment uses an FPGA (field programmable gate array) chip inside the low-level system 1 to generate a sawtooth pulse to drive the solid-state power source 2, the pulse width of the sawtooth pulse is adjustable, the phase is set to 0 degrees, the nonlinear characteristic curve can be calculated according to the input and output signals of the solid-state power source 1, and the nonlinear characteristic curve should include two characteristic curves of amplitude modulation-amplitude modulation (AM-AM) and amplitude modulation-phase modulation (AM-PM), wherein AM-AM is the input amplitude to the output amplitude, and AM-PM is the input amplitude to the output phase.
Furthermore, in order to avoid the triggering of faults of the superconducting cavity when the solid-state power source is in saturated output (due to overlarge electric field), the superconducting cavity needs to be detuned in advance before measurement, and the specific method is as follows: and adjusting the resonance frequency of the superconducting cavity by using the tuner, so that the resonance frequency of the superconducting cavity is smaller than the frequency of the radio frequency signal, and the detuning frequency is larger than 10 times of the bandwidth of the superconducting cavity.
S2, calculating a predistortion function for realizing nonlinear compensation according to the nonlinear characteristic curve obtained in the step S1.
Specifically, the predistortion function includes an amplitude predistortion function and a phase predistortion function, which can be derived from two characteristic curves of AM-AM and AM-PM through formulas.
And S3, carrying out linearization compensation on an input signal of the solid-state power source according to the predistortion function, so that the compensated power source can reach a loop gain similar to a linear region even if working in a near saturation region.
Specifically, in this embodiment, a predistortion module is disposed in a low-level system FPGA chip, where the predistortion module in the FPGA chip is divided into an amplitude predistortion module and a phase predistortion module, and the amplitude predistortion function and the phase predistortion function obtained in the step S2 are respectively disposed.
Further, the amplitude predistortion function and the phase predistortion function are both look-up tables. The address of the lookup table is the amplitude of the low-level output control signal, and the data in the lookup table is the discrete value of the amplitude and phase predistortion function.
The implementation process of the solid-state power source linearization method provided by the invention is described in detail below through a specific embodiment.
In this embodiment, as shown in FIG. 8, the solid state power sources 2 are manufactured by Katen corporation, each of which contains 24 inserts (model: KFAA-162-1-1), and the saturated output power of a single insert is about 1.4kW; the superconducting cavity 5 is a half wavelength superconducting cavity (HWR 010, the relativistic speed of which is 0.1); the FPGA chip model of the low-level system 1 is ZYNQ7100. Based on the above parameter settings, the solid-state power source linearization method provided by the present embodiment includes:
1. a measurement phase of the nonlinear curve of the solid state power source.
Generating sawtooth wave pulse by the low level system 1 to drive the solid state power source 2, calculating the nonlinear curve of the solid state power source 2 according to the input and output signals of the solid state power source 2, comprising:
1. the superconducting cavity is detuned by the tuner, so that the resonance frequency of the superconducting cavity 5 is smaller than the frequency of the radio frequency signal, and the detuning frequency is larger than 10 times of the bandwidth of the superconducting cavity.
2. As shown in fig. 3, the sawtooth pulse signal is encoded and outputted in the FPGA chip of the low level system 1, the pulse width is 2 to 10 minutes, and the pulse phase is set to 0 degrees. When selecting the pulse maximum, it is necessary to ensure that the solid state power source 2 can operate in the saturation region and maintain the saturated output power for about 15-25 seconds.
3. The response signal of the solid-state power source 2 to the above mentioned sawtooth pulse is read in the low-level system 1 and connected to the coupling terminal of the directional coupler 3 (model: EXIR MDIR-2077-33-A, directivity: >40 dB).
4. According to the input and output signals of the solid-state power source 2, two nonlinear curves of AM-AM and AM-PM are calculated, as shown in FIG. 3, the abscissa of the AM-AM curve is the amplitude of the sawtooth pulse of FIG. 2, and the ordinate of the AM-AM curve is the amplitude of the response signal of FIG. 2. The input and output signals are based on the same clock, so that the amplitude of the sawtooth wave pulse and the amplitude of the response signal are in one-to-one correspondence. Similarly, the abscissa of the AM-PM curve is the amplitude of the sawtooth pulse of fig. 2, and the ordinate of the AM-PM curve is the phase of the response signal of fig. 2, which are in one-to-one correspondence. Next, two nonlinear characteristic functions f (x) and θ (x) are obtained by fitting a 10 th order polynomial based on the nonlinear curve. The independent variable x is the amplitude of the sawtooth pulse, and the functions f (x) and θ (x) are the amplitude and the phase of the solid-state power source response signal measured by the low-level system, as shown in fig. 4.
2. Predistortion function solving stage
The predistortion function solution according to the characteristic functions f (x) and theta (x), the amplitude and phase predistortion function needed for finishing nonlinear compensation is solved, comprising:
1. assuming that the solid-state power source inputs sawtooth pulse with amplitude X sat Time output saturation (definition X sat Saturation point), its corresponding output is Y sat ＝f(X sat ) Function h (X) = (X) defining normalized AM-AM characteristic curve sat /Y sat )f(x)。
2. The magnitude predistortion function g (x) is the inverse of h (x) above, i.e., g (x) =h -1 (x)；
3. The phase predistortion function is a complex function phi (x) = -theta [ g (x) ].
In this embodiment, the shapes of g (x) and phi (x) are shown in fig. 4.
3. And a deployment stage of the predistortion module.
In this embodiment, an amplitude and phase predistortion module is built in the FPGA, and values of predistortion functions g (x) and phi (x) are stored in an amplitude and phase lookup table in the predistortion module.
Further, according to the hardware parameters of the FPGA chip, in this embodiment, the upper 15 bits (excluding the sign bit) of the 32-bit low-level amplitude control signal are intercepted as the addresses of the lookup table, and the discrete values of g (x) and phi (x) are stored in the amplitude-phase lookup table respectively.
Further, the process of making the amplitude and phase lookup table includes:
g (x) and phi (x) are discretized into g (n) and phi (n) according to the amplitude predistortion function and the phase predistortion function, respectively. Wherein the unsigned number n is a high 15-bit low-level amplitude control signal after interception, as shown in FIG. 5, the value range is 0 to 32767 (i.e. 2 15 -1). When n is less than or equal to saturation point X sat When the predistortion functions g (X) and phi (X) are directly calculated, the values of x=0, 1,2 and … X sat The values at g (n) and phi (n). When n is greater than X sat When g (n) and phi (n) are respectively constant equal to the constant g (X) sat ) Phi (X) sat ). Specifically, the solving algorithm of g (n) and phi (n) is shown in the following formula. The discretization process by the amplitude predistortion function g (x) is illustrated as shown in fig. 6 (a) and 6 (b).
Further, g (n) and φ (n) are written into the amplitude and phase lookup tables in FIG. 6, respectively. For ease of understanding, the addresses and data in the amplitude lookup table are illustrated as shown in fig. 6 (c). After a predistortion module is embedded in the FPGA chip of the low-level system 1, nonlinear compensation of amplitude and phase can be realized.
As shown in fig. 7, it is assumed that the current low level system amplitude control signal is a (as above, a is an unsigned number between 0 and 32767) and the phase signal is 0; because the addresses of the amplitude phase lookup tables in the predistortion module are all a, the amplitude and the phase of the output signals are the outputs g (a) and phi (a) of the amplitude lookup tables and the phase lookup tables. Further, since the AM-AM nonlinear characteristic curve AM-PM nonlinear characteristic curve of the power source is f (x) and θ (x) respectively, the amplitude and phase of the predistortion output signal after nonlinear transformation of the power source are f [ g (a) respectively]And phi (a) +theta [ g (a)]. As described above, since f (x) = (Y) sat /X sat )h(x)，g(x)＝h -1 (x) The amplitude of the power source output signal is f [ g (a) ]]＝(Y sat /X sat ) a, thereby achieving linearization of the amplitude. Similarly, since φ (x) = - θ [ g (x)]The phase phi (a) +theta (g (a) of the power source output signal]=0, thereby achieving phase linearization. Note that when the system amplitude control signal a is initially low>X sat When the power source reaches saturation, the output value is constant at saturation value Y sat . In summary, the predistortion module and the solid state power source achieve linearization of the overall AM-AM and AM-PM characteristic curves.
4. And a performance evaluation stage.
Specifically, the solid-state power source 2 is driven after the same sawtooth pulse is subjected to predistortion treatment by the predistortion module, and the output signal of the solid-state power source 2 is measured by the coupling end of the directional coupler 3. And finally, evaluating indexes such as linearity of the AM-AM curve, peak-to-peak error of the AM-PM curve and the like.
Specifically, in this embodiment, the sawtooth pulse signal generated by the low level system 1 is predistorted by the predistortion module to drive the solid-state power source 2. Reading a response signal of a sawtooth pulse in the low-level system 1, and calculating the integral AM-AM and AM-PM characteristic curves of the solid-state power source after the predistortion module:
the amplitude curve of the original sawtooth pulse is changed into g (x) through amplitude predistortion, wherein x is the amplitude of the sawtooth pulse and is an inverse function with the AM-AM curve of the power source;
through phase predistortion, the phase curve of the original sawtooth pulse is changed into phi (x), wherein x is the amplitude of the sawtooth pulse, phi (x) = -theta [ g (x) ], and the AM-PM curve of the power source are mutually offset, and after nonlinear transformation of the power source, the phase of the amplitude curve is still the phase of the original sawtooth pulse;
and calculating the linearity of the integral AM-AM curve and the phase deviation of the AM-PM curve after the predistortion module, and evaluating the linearization effect, wherein after nonlinear compensation, the integral AM-AM and AM-PM characteristic curves are improved as shown in figure 9.
Embodiment two: as shown in fig. 8, the present embodiment further provides a solid-state power source linearization system for a particle accelerator, including a low-level system 1, a solid-state power source 2, a directional coupler 3, and an input coupler 4;
the output end of the low level system 1 is connected with the input end of the solid state power source 2, the output end of the solid state power source 2 is connected with the input end of the directional coupler 3, and the output end of the directional coupler 3 is fed into the radio frequency superconducting cavity 5 through the input coupler 4. Wherein the output of the solid state power source 2 is further connected to the low level system 1 via a coupling of the directional coupler 3.
In a preferred embodiment of the present invention, the FPGA chip of the low-level system 1 includes a sawtooth pulse signal generator and a predistortion module;
the sawtooth wave pulse signal generator is used for outputting sawtooth wave pulse to drive the solid-state power source;
and the predistortion module is used for carrying out linearization compensation on the input signal of the solid-state power source according to the set predistortion function, so that the compensated power source can reach a loop gain similar to a linear region even if working in a near saturation region.
Further, the obtaining process of the predistortion function includes:
on-line measuring the input-output nonlinear characteristic curve of the solid-state power source;
and calculating a predistortion function for realizing nonlinear compensation according to the obtained nonlinear characteristic curve, wherein the predistortion function comprises an amplitude predistortion function and a phase predistortion function. Since the acquisition of the predistortion function in the embodiment is basically similar to the method embodiment, the description process in the embodiment is relatively simple, and the relevant points can be referred to the part of the description in the first embodiment, which is not repeated here.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In the description of the present specification, reference to the term "one preferred embodiment," "in this embodiment," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiment of the present specification. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for linearizing a solid state power source for a particle accelerator, comprising:
acquiring an input signal of a fixed power source;
and carrying out nonlinear compensation on the input signal of the solid-state power source according to the predistortion function.
2. The method of linearizing a solid state power source according to claim 1, characterized in that the superconducting cavity is detuned beforehand, in particular: and adjusting the resonance frequency of the superconducting cavity by using the tuner, so that the resonance frequency of the superconducting cavity is smaller than the frequency of the radio frequency signal, and the detuning frequency is larger than 10 times of the bandwidth of the superconducting cavity.
3. A method of linearizing a solid state power source as in claim 1 or 2, wherein the obtaining of the predistortion function comprises:
measuring an input-output nonlinear characteristic curve of the solid-state power source;
and calculating a predistortion function based on the input-output nonlinear characteristic curve, wherein the predistortion function comprises an amplitude predistortion function and a phase predistortion function.
4. A method of linearizing a solid state power source as in claim 3, wherein the input-output nonlinearity curve of the solid state power source comprises an AM-AM nonlinearity curve and an AM-PM nonlinearity curve, wherein AM-AM is the input amplitude to the output amplitude and AM-PM is the input amplitude to the output phase.
5. The method of claim 4, wherein the magnitude predistortion function and the phase predistortion function are obtained by solving a measured magnitude f (x) and a measured phase θ (x) of a response signal of the solid state power source, and the method comprises:
the solid-state power source has an input pulse amplitude of X sat Saturated output corresponding to Y sat ＝f(X sat )；
Function h (X) = (X) defining normalized AM-AM characteristic curve sat /Y sat )f(x)；
The magnitude predistortion function g (x) is the inverse of h (x) above, i.e., g (x) =h -1 (x)；
The phase predistortion function is a complex function phi (x) = -theta [ g (x) ].
6. A method of linearizing a solid state power source as in claim 3, wherein the magnitude predistortion function and the phase predistortion function are both lookup tables, the lookup tables including addresses and data, wherein the addresses of the lookup tables are the magnitude of the input pulse signal and the data in the lookup tables are discrete values of the magnitude predistortion function or the phase predistortion function.
7. The method of claim 6, wherein the process of creating the amplitude and phase look-up table comprises:
discretizing g (x) and phi (x) into g (n) and phi (n) according to an amplitude predistortion function and a phase predistortion function, wherein the unsigned number n is the amplitude of the intercepted high 15-bit input pulse signal, and the value range is 0 to 32767;
when n is less than or equal to saturation point X sat When the predistortion functions g (X) and phi (X) are directly calculated, the values of x=0, 1,2 and … X sat The values at are g (n) and phi (n), when n is greater than saturation point X sat When g (n) and phi (n) are respectively constant equal to the constant g (X) sat ) Phi (X) sat )；
And writing g (n) and phi (n) into data in the amplitude or phase lookup table to obtain data corresponding to each address, and completing the manufacture of the amplitude or phase lookup table.
8. A solid state power source linearization system for a particle accelerator, the system comprising a low level system, a solid state power source, a directional coupler, and an input coupler;
the output end of the low-level system is connected with the input end of the solid-state power source, the output end of the solid-state power source is connected with the input end of the directional coupler, the output end of the directional coupler is fed into the superconducting cavity through the input coupler, and the output end of the solid-state power source is also connected with the low-level system through the coupling end of the directional coupler.
9. The solid state power source linearization system of claim 8, wherein the low level system is implemented by an FPGA chip comprising a sawtooth pulse signal generator and a predistortion module;
the sawtooth wave pulse signal generator is used for outputting pulse to drive the solid-state power source;
the predistortion module is used for carrying out nonlinear compensation on an input signal of the solid-state power source according to the set predistortion function.
10. The solid state power source linearization system of claim 9, wherein the process of obtaining the predistortion function comprises:
measuring an AM-AM nonlinear characteristic curve and an AM-PM nonlinear characteristic curve of a solid-state power source, wherein AM-AM is input amplitude to output amplitude, and AM-PM is input amplitude to output phase;
and calculating a predistortion function based on the AM-AM nonlinear characteristic curve and the AM-PM nonlinear characteristic curve, wherein the predistortion function comprises an amplitude predistortion function and a phase predistortion function.
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| CN113162559A (en) * | 2021-03-30 | 2021-07-23 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Millimeter wave self-adaptive predistortion linearized solid-state power amplifier |
| CN114051309A (en) * | 2021-11-03 | 2022-02-15 | 北京航天广通科技有限公司分公司 | Control system and method for radio frequency power and amplitude of particle accelerator |
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| CN110705085A (en) * | 2019-09-26 | 2020-01-17 | 中国科学院近代物理研究所 | Control method and system for high-frequency digital low level in single sine mode of accelerator |
| CN113162559A (en) * | 2021-03-30 | 2021-07-23 | 西南电子技术研究所（中国电子科技集团公司第十研究所） | Millimeter wave self-adaptive predistortion linearized solid-state power amplifier |
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